Electric oven.



J. G. vGRONBERG Iz/W. D. HUDSON. ELECTRIC OVEN.

PPLIGATION FILED 11:13.15, 1909.

1 ,022,545. Patented Apr. 9, 1912.

J. G. GRONBERG &'W. D.' HUDSON. BLEGTRIG OVEN. APPLIGATION FILED 213.15,1909.

1,022,545. Patented Apr.9,1912.

5 SHEETS-SHEET 2.

J. G. GRONBERG & W. D. HUDSON. ELECTRIC OVEN. APYLIOATIUN vFILED PEB.15,1909.

Patented Apr. 9, 1912. 5 SHEETS-SEEET 3.

J. G. GRONBERG 61: W. D. HODSON.

ELECTRIC OVEN. APPLICATION FILED P21345, 1909.

5 SHEETS-SHEET 4.

fe//zW-, f Jg W Patented Apr. 9, 1912.

JfG. GRONBERG n W. D. HODSON.

ELECTRIC OVEN.

PPPPPPPPPPPPPPPPPPPPPPPPPPP 9.

Patented Apr. 9, 1912.

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UNITED sTATEs PATENT oEEicE.

JANESVILLE, WISCONSIN, ASSIGN ORS TO THE CALOBIC COMPANY, F JANESVILLE,ATISCONSIN, A CORPORATION OF WISCONSIN.

ELECTRIC OVEN.

Specification of Letters Patent.

Patented A pr. 9, 1912.

Application led February 15, 1909. Serial No. 478,012.

To all whom 'it may concern:

Be it known that we, JOHN G. GRONBERG and WALTER D. HoDsoN, citizens ofthe llnited States, residing at Grand Rapids, in the county of Kent andState of Michigan, and Janesville, in the county of Rock and State oflVVisconsi'n, respectively, Ahave invented a certain new and usefulImprovement in Electric Ovens, of which the following is aspecification.

Our invention relates to electric ovens.

It is illustrated in the accompanying drawings, wherein- Figure l is avertical section through an oven arranged to receive our heating device:Fig. Q is a similar view at right angles to Fig. l; Fig. 3 is a planView of the controlling switch; Fig. 4 is a section of the controllingswitch showing a cut-Out magnet; Fig. 5 is a plan view of the lowersection of the heater plate, with parts removed; Fig. 6 is a crosssection therethrough; Fig. 7 is a plan view of the heater plate, andFig. 8 is a diagrammatic view showing the circuits.

Like parts are indicated by thel same letter in all the figures.

A A are the frame portions of a box or receptacle having the bottom A1,the top A2. the door A, the glass panels A4, the interior compartmentwallA5, the insulation packing A and the supporting legs A7. Inside theinterior com artment and forming the bottom thereof 1s the depressed panl provided preferably with a central depression B1 in which lies theterminal plate B2 which is secured in position by the bolts Bf' and isprovided with the rings B4, B5 and the central pin B, whence leadrespectively the conductors B7, B8 and B9 to the switch terminals. Thisswitch is shown as contained in the box C and consists of the table C1,the terminals C2, C3, whence lead the heater conductors B2 and B7respectively, the switch arms C4, C5 which make contact with theterminals C and C7,

whence lead the line wires C8 and Ctrespectiv'ely. The two switcharmsare connected by the cross ypiece C70 and have the controlling knobC11. They are associated with a spring C12 which 'tends to force themout so as to break the contact. Mounted on the switch is a cut-olfmagnet D having one end D1 of the pivoted armature exposed to it. Theother end of this armature is provided with a block D2 opposed to adetent D3 which is pivoted at D* and is adapted to engage a projectionD5 associated with the switch arms. These parts are secured in anydesired position as indicated in Fig. l where the switch arms are shownas thrown back by thespring C12. The conductor adapted to aid incontrolling the' cut-out magnet is indicated by the letter B9 and itleads from the central terminal B6 to the magnet D. The heating plateconsists of the body E which is preferably of 'soapstone, and the top E1likewise preferably of soapstone. In the body E are the conductor ringsE2, E3 and E4. The conductor ring E2 is adapted, when the plate is inposition, as indicated in Fig. 2, to make contact with the contact ringB,

while the conductor ring E3 makes contact 'Y with the contact ring B5,and the central terminal B makes contact with the headof a screw E5which bears against the contact ring E4. When the plate body E is placedwithin the receptacle as indicated in Fig. 2, these several rings whichit carries are thus in electrical connection with the severalvconductors above referred to.

On the top of the body E is formed a circular groove F. There are threesections to. this top of the body portion and we shall describe one ofthem. In one section of this groove is placed the terminal F1 inopposition to the terminal F2 which latter is in Contact with the outercoil of the resistance F3 which usually takes the shape of a ribbonwound with insulation between its several coils. Fromv this sameterminal F1 projects a two part curved thermostat spring F5 whichcarries at its outer end a contact point F5. This point is in oppositionto a contact point F6 associated with 'an inleading conductor F7 whichmakes contact with the contact ring E4 from which contact ring leads theconductor B9. Opposed to the terminal F1 is the terminal Fs whence leadsa conductor F9 to the outer contact ring E2 in the bottom of the heat-5' and 6,- we can trace these circuits. G is A a plug which, wheninserted, closes the conf dicated.as C8 and C9.

nection between the otherwise separated terminals F1 and F 8. Whenthisis done a circuit is created as follows, beginning at the line wiresback of the switch which are in- Assuming that the current is flowingthrough C9 in the direction indicated by the arrow, if the switch beclosed it will pass through the switch arm to the terminal C2, thencealong conductor BS to the inner ring E3, thence along the shortconductor Gr2 to the inner end of the resistance coil through theresistance coil to the terminal F2, through block G to terminal F8through conductor F to the outer ring E2, thence by the conductor B7 tothe other arm of the switch, thence out onto thel line wire C8. Thus acircuit is established through the resistance and heat begins to begenerated. 'As soon as sufficient heat has been generated to inwardlybend the resistL ance spring Ftanother circuit is established asfollows: through'conductor C9, through the switch arm terminal C2,through the cutout magnet D, along conductor Bg to the central contactring E4, thence along conductor F7 to the contacts F6 and F5 which arebrought int-o connection by the forward flexing of the spring F, thencealongv F* to the terminal F1, plug G, terminal F 8, conductor F", outerrin E2, conductor B7, and out in the other main line. This energizes themagnet D, causing it to bring down its armature in the structure shownin Fig. 1 o r in the struct-ure shown diagrammatically in Fig. 8,whereupon the switch arm is revleased and the spring C12 forces it outas shown in Fig. l, thus breaking both circuits.

G1 G1 are stop screws to vary the tension on the springs F t and thusvary the time within which, at a given heat, they will be sutlicientlyflexed to close their respective circuits.` The. arrangement of thesestop screws and thermostat springs is such as to give three differingresults. If a temperature of a certain height will flex the first ofthese springs, the set screws are so adjusted on the others that onehundred degrees more of heat is required before the second one isflexed, and a still higher degree before the third is flexed, or, if theparts are properly adjusted, they may be so arranged that it will take acertain amount of time at a given temperature to flex yeach spring andthey will vary among themselves as to time. The Objectis to have avariation between these several thermostatic invention. We shall setforth in the claims what appears to be essential.

`The top ofthe heating plate J is preferably inthe shape of an inverteddish, cut out at J? and it is perforated at J2. Its lower rim J3 isslotted as at J to admit air under the rim into the interior of the dishabove the heating coil and to permit such air when heated to pass outthe holes.

Mounted on the top of the heating plate `is the-cover K preferablycorrugated as indicated at K1 and provided with a ring K2 whichoverhangs the top of the heating plate. It is secured in position by thebolts and nuts K3 K3. These radial corrugations leave inwardly opengrooves Kx K* wherebyT the air escapes from under the cover and aroundits edges at the centralopening K1. For convenience we have connectedthe inner end of the coil with la ring L to which the conductor leadsand we have surrounded the coil with a ring M to which the conductorleads.

The use and operation of our invention is as follows: An oven of thetype shown in Fig. 2 having been provided, the switch is in position onthe side and the three conductors are brought down inside and secured tothe three terminals or contacts in the tei'- minal plate in' the bottomof the receptacle. The heating plate, having its several parts properlyarranged and associated together as indicated, for example, in Fig. 6,is then placed in position in the bottom of the receptacle on top of theterminal plate, its two terminal rings and terminal center piece beingplaced in position so as to make electrical contact with the threecontact rings on the bottom ot the plate body. This leaves the parts inthe position where the heating plate is resting on the terminal plate inthe bottom of the receptacle indicated in Fig. 1. The switch is open asindicated in Fig. 1. The plug G is inserted between the predeterminedpair of coil and cut-out terminals. The operator will select that pairwhich will bring into play the particular thermostatic spring which hedesires to have acted upon. The objects or materials to be subjectedvtothe heat are then placed in position on the cover of the heating plateand the switch is closed. Thereupon the current, as previously describedthrouv h the switch or lnleading wires C and C", 1s supplied whichtraverses the heating coil until the plate has been raised to a certaintemperature or kept at a certain temperature for a certain predeterminedtime. Thereupon the thermostaticspring F, associated with the plug G, ismoved forward until the points F5 and F 5 contact, whereupon a circuitis made through the cut-out magnet D. This magnet throws down itsarmature, releases the handle and permits the spring C12 to open theswitch and the current is cut off from both the mag: net and heatingcoil. It will be understood that these heating plates could be 'arrangedin any desired manner or that there might be a series of them in thereceptacle, 'for eX- ample, one at the top and one at the bottom. Itwill also be understood that these receptacles and plates while shown ascircular in outline, may be ofany desired shape. Any species of switchcan be used. Soapstone is the preferred material though other substancesmight be employed.

Broadly speaking, our invention embraces a switch, a cut-out, a heatingcoil, circuit closers whereby )a current' can be made to traverse theheating coil, a .thermostatic circuit closer whereby a currentmay bemade to traverse the cut-out responsive to variations in heat of theheating coil, and means whereby the cut-out can shut ofthe current fromthe heating coil.

The dish shaped bottom of the oven is intended to receive and drain awayfrom the eenterthe grease or other liquid whichmay tend to collect inthe bottom of the oven. The series of thermostatic devices, and theremay of course be any number of them, are to be adjusted and adaptedsothat when a sufficient degree of heat has been obtained or when the,heat is continued for a suilicient length of time, the supply ofcurrent will be automatically cuthotl" after which, of n course, theheat remains without further '1ncrease and practically at. a uniformstage for an indefinite period. One advantage of this arrangement isthat no attention is required# as the user may, upon applying thecurrent by throwing the switch, the oven being closed and the cookingutensils in position, go away and leave the apparatus, knowing thatthere is no danger of overheating, and even assured that the requisiteamount of heat will be obtained and that the device will thenautomatically cut itself out of further current supply.

Our invention can be used for enameling ovens, hot water heatin systems,and other purposes as well as for eless cook stoves.

We claim:

1. In a heater, the combination of a heating plate comprising abody anda top.with intermediate space with a heating coil associated therewith,anelectric supply circuit connected with the heating coil, a circuitbreaker therefor, an electric circuit for said circuit breaker,additional means for closing the supply circuit and means yresponsive tothe temperature for operating the circuit breaker to stop the heatingprocess when any predetermined temperature has once been reached. v

2. In a heater, the combination of a heating plate comprising a body anda top, with an air circulating space between them, a heating coilassociated therewith, an electric supply circuit connected with theheatin\g coil, a circuit breaker therefor, additional means for closingthe supply circuit, and means responsive to the temperature foroperating the circuit breaker to stop the heating process when once anypredetermined temperature has been reached.

3. In a heater, the combination of a heating plate comprising a body anda top having discharge openings therethrough with an air space betweenthem, and side inleading openings, a heating coil associated therewith,an electric lsupply circuit connected with the heating coil, a circuitbreaker therefor, additional means for lclosing the supply circuit, andmeans responsive to the temperature for operating the circuit breaker tostop the heating process when any predetermined temperature has oncebeen reached.

4. In a heater, t-he combination of a heating plate comprising a body, atop and cover, with air circulating spaces between them, a heating coilassociated therewith, an 'electric supply circuit connected with theheating coil, a circuit breaker therefor, additional means for' closingthe supply circuit, and means responsive to the temperature foroperating the circuit breaker to stop the heating process when any'predetermined 'temperature has once been reached.

5. In a heater, the combination of a heating plate comprising a body anda top, with a space .between them and a corrugated cover on the top,with a space between it and the top, a heating coil associatedtherewith, an electric supply circuit connected with the heating coil, acircuit breaker therefor, additional means for closing the supplycircuit, and means for operating the circuit breaker responsive tovariations' in heat.

6. In a heater, the combination of a heating plate comprising a body, atop and a cover having opening therethrough, an air space between thetop and cover and' the `body and top, said space having outsideopenings, a heating coil, associated therewith, any electric supplycircuit connected with the heating coil, a circuit breaker therefor,additional means for closing the supply circuit and means for operatingthe circuit breaker responsive to variations in the temperature.

7. In a heater, the combination of a receptacle with a terminal plate inthe bottom thereof, a heating plate resting on such terminal and inelectrical contact therewith,` a heating coil associated therewith, anelectric supply circuit connected with the heating coil, a circuitbreaker therefor, and means responsive to the temperature for operatingthe circuit breaker to stop the heating process lwhen any predeterminedtemperature has once been reached. y

8.'In a heater, the combination of a heating plate with a heating coilassociated therewith, an electric supply circuit connected with theheating coil, a circuit breaker therefor, additional means for closingthe supply circuit, and means responsive to the temperature foroperating the circuit breaker to stop the heating process when anypredetermined temperature has once been reached, a terminal plate onwhich the heating plate rests, and with which it is in electricalcontact, and conductors leading from the outside to the terminal plateand forming part of the electric supply current.

9. Ina heater, the combination of a heating plate with a heating coilassociated therewith, an electric supply circuit connected with theheating coil, a circuit breaker therefor, additional means for closingthe supply circuit, means responsive to the temperature for operatingthe circuit breaker to stop the heating process when any predeterminedtemperature has once been reached, an inclosing receptacle, a terminalplate in the bottom of the same on which the heating plate rests andwhich is in electrical contact therewith, and conductors from theterminal plate to the circuit breaker operating devices.

10. In a heater the combination with a heating plate of heating meanstherewith, comprising a pair of terminal rings one within theother acoil surrounding said rings and terminating at either end in one ofthem, av switch, and a conductor connecting said switch andA said ringsand means connecting` said switch with any suitable source of power. 1

11. In a heater the combination with a heating plate of heating meanstherewith,

A comprising apair of terminal rings one `within the other, a coilsurrounding said rings and terminating at either-end in oneo them, aswitch and a conductor connecting saidswitch and said rings and aconnection between said switch and any suit-able source of power, andelectric magnetically controlled operating means for saidswitch.

12. In a heater' the combination with a heating plate of heating-meanstherewith,

p 1,022,545 l l comprising a pair of terminal rings one within theother, a coil surrounding said rin s and terminating at either end inone of t em, a switch and a conductor connecting said switch and saidrings and a connection between said switch and any suitable source ofpower, and electromagnetically controlled operating means for saidswitch, a terminal concentric with said rings and a circuit from one ofthe terminals of said switch through said magnetic means to saidterminal, thermostats disposed about said coil and communications fromsaid center terminal to one of the terminals of said thermostat aremovable connection between the other terminalof said thermostat andthe outer terminal ring.

13. In a heater, the combinationl of a heating plate with a heating coilassociated therewith, an4 electric supply circuit connected with the twoends of the heating coil, a circuit breaker therefor, means including anelectric circuit for operating the circuit breaker, and means consistingof a removable plug for simultaneously closing the two circuits.

14. In a heater, the combination of a heating plate with a heating coilassociated therewith, an electric supply circuit connected with vthe twoends of the heating coil, a circuit breaker therefor, means includinganvelectric circuit for operating the circuit breaker, and athermostatic circuit closer in such circuit, and means consisting of aremovable plug for simultaneously c osing the two circuits. 1

15. In a heater, the combination of a heating late with a heating coilassociated therewit an electric supply circuit connected with the twoends of the heating coil, circuit breaker therefor, means includinganelectric circuit for operating the circuit breaker, and athermost-atic circuit closing device in proximity to the heating plateand responsive to variations in heat, and means consisting of aremovable plug for simultaneously closing the two circuits.

16. In a heater, the combination of a heating plate with a heatingcoilassociated therewith and laid thereon, an outer conducting riiig withinthe coil, an inner conducting ring within the coil, a supply circuitconnected at its terminals with the inner and outer rings respectively,a switch in the supply circuit, and a series of means for throwing theswitch unequally, responsive to variations inthe heat of the plate.

17. In an electric oven, the combination of a receptacle with a centralterminal block therein, a heating plate supported thereon, and mutuallycontacting rings on plate and block whereby the electric circuits areestab- Y of a receptacle with a central terminal block thereof, aheating plate 'resting upon the 10 therein, a heating plate supportedthereon support, and an outwardly inclined collectund mutuallycontacting rings on plate and ing dish-in the bottom of such oven.

block whereby theelectric circuits are estab- JOHN G GRONBERG lishedwhen the plate is put in position on the block, and a supply currentwith a switch WALTER D' HODSON' on the outside of the oven. Witnesses:

19. In an electric heater, the combination H. K. DEAN,

of an oven with a support in the bottom A. T. THoR'rs.

